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Date: Tue, 26 Dec 2006 12:21:29 -0500
From: Christopher Faylor <cgf-use-the-mailinglist-please AT cygwin DOT com>
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Subject: Re: Updated cygwin dlls cause unnecessary reboot on NT
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On Tue, Dec 26, 2006 at 02:38:03PM +0000, Max Bowsher wrote:
>Linda Walsh wrote:
>>    The fix I proposed has nothing to do with the cygwin1.dll.  As has
>> been covered previously, since cygwin1.dll and a few other libs are
>> part of the cygwin "kernel", special handling may be needed to upgrade
>> those dll's.  What can be fixed is the installation of .exe and .dll
>> files for
>> applications.  The behavior of those should be the same as replacing
>> in-use .so's and executables on *nix.
>
>I believe there is a critical element you have missed.
>
>In order to perform the rather miraculous emulation of fork(), Cygwin
>needs to reload all the same DLLs that are operating in one process into
>another newly created process. Updating the DLL files on disk whilst
>processes are using them prevents this from happening.
>
>For a simple demonstration of this:
>
>* Start a bash shell
>* Rename any of the DLLs used by bash to something else
>* Try to execute any non-builtin command
>* See the fork failure message
>
>Could this be worked around? Perhaps.
>Is it likely to happen? No, the benefit-to-work ratio is too low.

Thanks for adding a piece of the puzzle, Max.

This is a reason why just renaming an in-use dll is not going to work
and creation of .new files is required.

cgf

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